1. Field of the Invention
The present invention relates to an apparatus and method for producing a rapid time-related three dimensional image with a numerical profile of an object. More particularly, it involves projecting complex digitally based patterns or scanning laser beam(s) on to the object, photographing these patterns with a fast response digital camera, and rapidly calculating a dimensional map of the contours, edges, and openings of the object.
2. Description of Related Art
In 1905, Albert Einstein, who at that time was a patent examiner in Zurich, developed the Special Theory of Relativity which emphasized the importance of considering time in addition to the three dimensions of space in describing the behavior of matter and energy. In accordance with this concept, creating three dimensional profiling images in a very short time period is very useful in order to record a plethora of fundamental dynamic observations in physics, chemistry, biology, microscopy, medicine, and engineering. It also has a particular application to identification procedures for security applications.
Stereoscopic photography was invented in the nineteenth century, and has been developed since then to create very colorful stereoscopic movies. In contrast, the development of stereoscopic profiling with accurate detailed measurements of three dimensional objects has been difficult to achieve. The development of digital photography and fast computation using fast digital processing has now provided the possibility of accurate stereoscopic imaging with detailed dimensional measurements of the contours of an object in real time.
Presently used techniques for non-invasive three dimensional imaging with digital detailing of an object utilize a variety of systems. One technique is the use of time of flight of a pulsed laser whereby the distance from the laser to the object is determined by measuring the transit time of the laser beam. This procedure, described by Cameron, et al in U.S. Pat. No. 5,006,721 provides fairly accurate digital topographical data. A commercial version of the laser ranging system is manufactured by Cyrax Technologies, and several other companies. While such systems provide good three dimensional data, they involve a quite costly apparatus because the time of flight must be measured to a few picoseconds, and the mirrors used to direct the laser beam as well as the mirrors used to route the reflected beam must be exact to a small division of a minute of arc. In addition, the scanning of a three dimensional object with a laser beam requires a considerable length of time, due to the fact that each incremental point on the surface of an object must be illuminated by the beam and the time of flight measured, resulting in a finite (and relatively long) time for all points to be illuminated and surveyed.
Another technique is the use of stereographic projections of a grid. This procedure, as described by M. Proesmans, et al. In U.S. Pat. No. 6,510,244 B2, issued Jan. 21, 2003, describes the use of a projected grid for topographic imaging. They describe a grid projection with a camera directed to provide three dimensional imaging. The use of such relatively static methods does not provide for the real-time measurement of dynamic details needed for dynamically imaging and measuring surface contour dimensions of objects which have movement, such as a bridge or beam undergoing stresses and strains. As stated in their patent, their application is “aimed at showing and not measuring the object.”
Applications such as rapid reverse engineering with dynamic considerations of stress-strain relationships, measurements of flexure of mechanical and civil structures such as airplanes, vehicles, bridges, pipes, pipelines, steel tanks, autos and ships require very fast imaging techniques for which this invention is designed and applicable. In such applications as human body imaging where, due to breathing and heart motion, it is important to consider the time aspect of imaging in order to acquire realistic measurements of the body. There is a need for such rapid imaging procedures in medical analyses, for example, in following the progress, and in determination of the efficacy of treatments of such diseases as osteoporosis and skin cancers as well as other skin and body medical problems.